INERTIA Setting
Moment of Inertia and INERTIA Setting
The moment of inertia is a quantity that expresses how hard it is for an object to turn, and it is expressed in terms of values for the moment of inertia, inertia, or GD2. When a hand or other object is attached to the Arm #6 for operation, the moment of inertia of the load must be taken into consideration.
CAUTION
The moment of inertia of the load (hand + workpiece) must be 0.2 kg·m2 or less.
The C12 Manipulators are not designed to work with a moment of inertia exceeding 0.2 kg·m2. Always set the value corresponding to the moment of inertia. Setting a parameter value that is smaller than the actual moment of inertia may cause errors or impact, may prevent the Manipulator from working at full functionality, and may shorten the lifespan of mechanical parts.
The allowable moment of inertia of a load for C12 Manipulators is 0.03 kg·m2 at the default rating and 0.2 kg·m2 at the maximum. Change the setting of the moment of inertia according to the inertia moment of the load using the INERTIA command. After the setting is changed, the maximum acceleration/deceleration of Arm #6 that corresponds to the "Inertia" value is corrected automatically.
Moment of Inertia of Load Attached to Arm #6
The moment of inertia of the load (hand + workpiece) attached to the Arm #6 can be set by the "Inertia" parameter in the Inertia statement.
Go to [Tools] - [Robot Manager] - [Inertia] panel, and enter the value in [Inertia]. This can also be set using the Inertia statement in [Command Window].
Eccentricity and INERTIA Setting
CAUTION
- The eccentricity of the load (hand + workpiece) must be 300 mm or less. The C12 series Manipulators are not designed to work with eccentricities exceeding 300 mm. Always set the value based on the eccentricity. Setting the eccentricity parameter to a value smaller than the actual eccentricity may cause errors or impact that not only impair full functionality but also shorten the life of the mechanical components.
The allowable eccentricity of load for C12 Manipulators is 50 mm at the default rating and 300 mm at the maximum. When the load eccentricity exceeds the rating, change the setting for the eccentricity parameter in Inertia statement. After the setting is changed, the maximum acceleration/deceleration of the Manipulator that corresponds to the "Eccentricity" is corrected automatically.
Eccentricity
| Symbol | Description |
|---|---|
| a | Rotation axis |
| b | Flange |
| c | Load center of gravity position |
| d, e | Eccentricity (300 mm or less) To set the parameter, enter the larger value of "d" or "e". |
Eccentricity of Load Attached to Arm #6
The eccentricity of the load (hand + workpiece) attached to the Arm #6 can be set by the "Eccentricity" parameter in the Inertia statement.
Enter the larger value of either "d" or "e" in the figure above to [Eccentricity].
Go to [Tools] - [Robot Manager] - [Inertia] panel, and enter the value in [Eccentricity]. This can also be set using the Inertia statement in [Command Window].
Automatic Acceleration/Deceleration Correction at INERTIA (Eccentricity) Setting
Automatic setting by inertia moment setting
* The percentages on the graph are ratios based on 100% as the acceleration/deceleration at the rated (0.03 kg·m2) setting.
Automatic setting by eccentricity setting
* The percentages on the graph are ratios based on 100% as the acceleration/deceleration at the rated (50 mm) setting.
Calculating the Moment of Inertia
An example of calculating the moment of inertia of a load (hand holding a workpiece) is shown below.
The moment of inertia of the entire load is calculated by the sum of (A), (B), and (C).
| Symbol | Description |
|---|---|
| a | Rotation axis |
| b | Shaft |
| A | Hand |
| B | Workpiece |
| C | Workpiece |
The methods for calculating the moment of inertia for (A), (B), and (C) are shown below. Use the moment of inertia of these basic shapes as a reference to find the moment of inertia of the entire load.
(A) Moment of inertia of a rectangular parallelepiped
| Symbol | Description |
|---|---|
| a | Rotation axis |
| b | Center of gravity of rectangular parallelepiped |
| m | Weight |
(B) Moment of inertia of a cylinder
| Symbol | Description |
|---|---|
| a | Center of gravity of cylinder |
| b | Rotation axis |
| m | Weight |
(C) Moment of inertia of a sphere
| Symbol | Description |
|---|---|
| a | Rotation axis |
| b | Center of gravity of sphere |
| m | Weight |